"No one in our shop anticipated us crossing the 800,000-voter registration mark," said Brian Miller, executive director of Nonprofit VOTE, who coordinates National Voter Registration Day.

The initial goal
was 300,000 registered voters, so the extra 500,000 voters came as a surprise to organizers.

Presidential elections typically are the most popular time to register to vote, but Miller credited the recent energy surrounding politics as a reason for the uptick.

"Midterm energy was absolutely critical. You can see all the poll data. A lot more people are paying attention to these midterms than you normally would have in a midterm cycle," Miller said.

The organization partnered with more than 4,000 groups
, like Facebook, Google, Twitter and Reddit, to spread the word to register.

National Voter Registration Day held or organized events across the country, from urban neighborhoods to rural communities, Miller added.

Rock the Vote
spokesman Andrew Feldman called the success of National Voter Registration Day "absolutely critical" for our democracy. The organization was one of the partners that focused on young voters.

"It means that folks are engaging in our democracy, and they get to have a real say," Feldman said. "We have seen so much engagement and activism in the last couple of years. That is fantastic, but to really have a say in our democracy you have to get out and vote."

Although voter registration for the midterms is still open
in all states, a fair amount of them don't allow registration within 30 days of the election. October 9 marks the last day to register to vote in one-third of states.